1. Field of the Invention
The present invention is directed to composite intermediate bonding structures and, more particularly, to composite intermediate bonding structures for joining together dissimilar materials.
2. Description of the Prior Art
There are frequent occurrences where two dissimilar materials must be joined together. When this occurs, frequently the surfaces are incompatible since a common adhesive may not be available to properly bond to both surfaces. Furthermore, in some circumstances, the material of one of the elements to be bonded together is more suitable to bonding by a heat melt process or by use of a solvent. Additionally, even where there is a method of bonding the two dissimilar elements together, the bonding method is usually a compromise and, therefore, the bond produced is not extremely strong and may be subject to deterioration with time.
One method which has been proposed in the past for bonding dissimilar articles is described in U.S. Pat. No. 4,273,827 (issued Jun. 16, 1981). The adhesive assembly therein described contains a first adhesive and a second adhesive which is of a different strength or chemical composition than the first adhesive. Positioned between the first and second adhesives is a barrier for preventing contamination of the respective adhesives or the substrate to which they adhere. The combination of adhesives includes a spongy or foam layer. At least one of the adhesives is encapsulated or retained in bubbles of a plastic film and is released by pressing the adhesive assembly against one of the substrates.
While this adhesive assembly is suitable for use with certain adhesives which may be readily encapsulated in bubbles of a plastic film, each adhesive assembly manufactured in the manner described therein is suitable for only certain substrate materials. Furthermore, certain adhesives cannot be encapsulated in this form and certain other techniques of bonding cannot be applied, such as the use of solvents or heat melting, to bond two dissimilar materials when using the adhesive assembly described therein.
What is needed, therefore, is an intermediate composite bonding structure which may be used with each of the various bonding methods, such as those involving heat melting, solvents, and adhesives. Furthermore, it would be useful if such a structure could be manufactured inexpensively. It would also be useful if such a structure could be easily adapted for use with several dissimilar materials.
A bonding method which is known in the orthodontic industry is described in U.S. Pat. No. 4,068,379, issued Jan. 17, 1978. This technology involves brazing or spot welding foil to a machined orthodontic bracket and diffusion bonding metallic mesh to the foil. The mesh is then adhesively bonded to the side of the tooth. This method works well for joining a metallic structure to the tooth, but in general still does not provide a method for joining any two dissimilar materials.
The purpose of the present invention, therefore, is to provide an intermediate composite bonding structure having two bonding faces separated by a non-porous base wherein the individual bonding faces may be bonded to elements having dissimilar materials to thereby join these elements together.